Oxygenated hydrocarbons, particularly methanol, have been used as feedstock to produce light olefins such as ethylene and propylene. In one particular process, methanol is converted to an olefin product containing a significant amount of light olefins, such as ethylene and propylene, by contacting the methanol with a molecular sieve catalyst. This type of process has generally been referred to as a methanol to olefin (MTO) reaction process.
Methanol that is used as feed for the MTO reaction process is typically produced from natural gas. Initially, the natural gas is converted to a syngas, which is a gas containing hydrogen, carbon monoxide and carbon dioxide. The syngas is then converted catalytically to a methanol composition, producing substantial quantities of water as a by-product. The methanol composition is then de-watered to form a substantially pure methanol composition, which is then transported and used as feed for the MTO reaction process.
Efforts have been directed to integrating the manufacture of methanol feed streams with the conversion of the methanol to form light olefins. For example, U.S. Pat. No. 5,714,662 (Vora et al.), discloses integrating a methanol synthesis system with a MTO reaction system. The disclosed process passes a crude methanol stream directly to the MTO reaction system for the production of light olefins.
U.S. Patent Publication No. US 2004/0127759 A1 discloses a process for producing light olefins by integrating a methanol synthesis system with a MTO reaction system. The intetrated system implements a shared separation system for separating oxygenate components from the respective methanol synthesis system and the MTO reaction system.
New ways of integrating methanol synthesis and the conversion of the methanol to olefin are continuously sought. Such systems require rather large amounts of energy to operate and energy savings are of particular importance. In addition, methods of operating such integrated systems are particularly complex, and complex systems are prone to bottlenecks. Accordingly, new methods of reducing or eliminating bottlenecks in huge complex systems are also of considerable demand.